ESP32 Bluetooth Audio Receiver with I2S output and volume control

I tried to use the A2DP_Sink_Example from Espressif. But there was one big drawback - the volume control over my smartphone didn't work. Instead I got disturbed sound from the ESP32 if I put the volume on my smartphone a little bit higher.

I fixed the code in the Espressif-example in order to control the volume over the smartphone once again properly.